Constraint Imperative Programming

这个项目继续研究约束命令式编程（CIP）语言。约束表示应该由计算机程序维护的关系。约束具有许多理想的属性，使它们在构建诸如交互式图形应用程序之类的系统时非常有用。它们是陈述句，而不是祈使句；程序员只需要说明“是什么”而不是“怎么做”。在编程语言本身中嵌入对约束的支持带来了额外的优势。首先，程序员可以方便地使用约束。其次，语言实现可以确保自动检查约束。第三，通过将标准结构表达为约束，可以产生更加统一和优雅的语言。最后，为编译器打开了更多的优化机会。在这个项目中，活动包括研究用于编译面向对象约束命令式语言（如Kaleidoscope）的技术，以生成高效的代码。为了实现这一点，系统对约束进行尽可能多的编译时分析。其他活动包括开发用于编写、浏览和调试约束命令式程序的工具，研究Kaleidoscope程序在共享内存MIMD机器上运行的编译，以及通过编写一组代表性应用程序来测试这类语言的实用性。另一个重要的焦点是开发更有效和强大的约束满足算法。最后一项活动是调试对约束系统的支持。约束满足算法和调试的工作对支持约束命令式语言和其他类型的基于约束的系统都是有用的。

This project continues work on Constraint Imperative Programming (CIP) languages. A constraint represents a relation that should be maintained by a computer program. Constraints have a number of desirable properties that make them useful in building systems such as interactive graphical applications. They are declarative statements, rather than imperative statement; a programmer need only to state ``what'' rather than ``how''. Additional advantages result from embedding support for constraints in the programming language itself. First, it becomes convenient for programmers to use constraints. Second, the language implementation can ensure that the constraints are checked automatically. Third, a more uniform and elegant language can result from expressing standard constructs as constraints. Finally, more opportunities for optimization are opened to the compiler. In this project, the activities include investigating techniques for compiling object-oriented constraint imperative languages, such as Kaleidoscope, to produce efficient code. To accomplish this, the system does as much compile time analysis of the constraints as possible. Other activities include developing tools for writing, browsing, and debugging constraint imperative programs, investigating the compilation of Kaleidoscope programs to run on shared memory MIMD machines, and testing the utility of this class of languages by programming a set of representative applications. Another important focus is the development of a more efficient and powerful constraint satisfaction algorithm. A final activity is work on debugging support for constraint systems. The work on constraint satisfaction algorithms and debugging is useful both to support constraint imperative languages, as well as other kinds of constraint-based systems.